In related art, a system analyzing device analyzes the state of packet communication in a system including a plurality of servers for packet communication and a switch for transferring a packet between the plurality of servers. For example, as depicted in FIG. 24A, a system analyzing device 100 analyzes packet communication between a server A 114A and a server B 114B via a switch 120SW.
Here, the switch 120SW has three ports 116P1 to 116P3. The server A 114A is connected to the port 116P1 of the switch 120SW. The server B 114B is connected to the port 116P2 of the switch 120SW. Packet communication between the server A 114A and the server B 114B is performed via the ports 116P1 and 116P2 of the switch 120SW.
The system analyzing device 100 sets the following mirroring to the switch 120SW in order to analyze packet communication between the server A 114A and the server B 114B. That is, the port 116P2, which is one of the ports 116P1 and 116P2 of the switch 120SW where packet communication is performed between the server A 114A and the server B 114B, is first set as a target port. The port 116P3, which is other than ports 116P1 and 116P2 and connected to the analyzing device 100, is set as an output port. A packet passing through the target port 116P2 is copied, and the generated packet is transmitted to the system analyzing device 100 via the output port 116P3.
Here, when packet communication is performed between the server A 114A and the server B 114B, a packet in this communication is copied when passing through the target port 116P2, and the packet generated by copying is outputted to the analyzing device 100 via the output port 116P3.
In the above example, communication between two servers A 114A and B 114B is described. In practice, however, communication is performed between more servers via a plurality of switches. FIG. 24B depicts an example in which communication is performed among three servers A 114A and C 114C via two switches 120SW1 and 120SW2. In this example, in mirroring of communication between the server B 114B and the server C 114C, a port 116P13 is set as a target port. In mirroring of communication between the server A 114A and the server B 114B, a port 116P11 is set as a target port. When a packet passing through these ports 116P11 and 116P13 is copied, and the packet generated by copying is transmitted to the system analyzing device 100 via an output port 116P14.
As related art, for example, Japanese National Publication of International Patent Application No. 2003-525000 and Japanese Laid-open Patent Publication No. 2013-30944 are disclosed.
However, when a packet is transferred, a port temporarily stores the received packet, and then transfers the stored packet. The port has a defined limit regarding a temporarily-storable packet data amount. Therefore, if copies of packets passing through the port 116P11 and the port 116P13 temporarily concentrate on the output port 116P14, any of the packets exceeding the limit is not stored in the output port 116P14 but discarded. The discarded packet is not outputted to the system analyzing device. If this situation continues, the system analyzing device may not be able to accurately analyze the state of packet communication on a packet-discarded side.